Just Once
by theliteraltrashcan
Summary: After 20 years, Osomatsu still finds himself utterly in love with his younger brother, Choromatsu. Ever since their kiss, he couldn't help but fall for him. Of course, he would never let him know. But what'll happen if Choromatsu finds out about his brother's feelings? Will he return them or...will he choose to never speak to Osomatsu again?
1. Chapter 1

_~flashback, 15 year old Matsuno's~_

"Choromatsu. Choromatsu, wake up." Osomatsu whispered softly into his brothers ear, gently shaking him in an attempt to wake him up. After a few minutes, seeing no progress in waking Choromatsu, he shoved him a bit, resulting in Choromatsu sitting straight up, quickly looking around like something bad was happening.

"Wha-!?" Choromatsu blinked a couple times only to see nothing but the faint figure of his eldest brother sitting up with him. He rubbed at his eyes, still half asleep. "Osomatsu nii-san?" he yawned. "What time is it?"

Osomatsu shrugged, looking at the clock behind them, seeing nothing but the fuzzy outline of the clock. "Probably like...two in the morning." Even with it being dark, he could tell that the look on Choromatsu's face was none too pleased, which made him laugh a bit. "I swear I didn't wake you up for something stupid."

A soft sigh left Choromatsu's lips as he rubbed his temples. "What could possibly be so important that you had to wake me up in the middle of the night?"

"Because it was keeping me up and I won't be able to fall asleep until I tell someone." Osomatsu leaned back a bit, keeping himself up with his hands behind his back. "I was just thinking..." having been such an open person, he wasn't at all worried about saying it, "what would it be like to, y'know...kiss a guy." He chuckled softly to himself. "I'm not saying I'm gay or anything, it's just...I'm curious."

Choromatsu groaned, lying back down and covering his head with the shared blanked. "If you're so curious, the go and kiss a guy, why should I care about what you do with your personal time?" He was only up for five minutes and he was already done with the day. Closing his eyes, he started falling asleep again, only to be moved by Osomatsu.

"Kiss me," Osomatsu whispered, lying down on his stomach next to his brother. "Just once. I swear I won't tell anyone."

The sudden request made Choromatsu's eyes shoot open, removing the blanket to stare at Osomatsu with wide eyes. He would deny it later, but it had made his face go complete red. At first, Choromatsu couldn't find the right words, his mouth only open slightly. He blinked before he glared at his brother, shaking his head, stuttering out his words. "N-no way, Osomatsu nii-san! Y-you're my older brother, it's disgusting! I'm going back to bed, goodnight!" He quickly covered his face, wanting to hide any proof that he was blushing.

"C'mon, pleeeeease?" Osomatsu begged, pouting out his lower lip, shaking Choromatsu lightly. "I promise I won't tell mom or dad or the others. I just need to know what it would be like." He shook him a little more harshly, whining a bit. "Please please please please pleeeeease? Just once?"

Choromatsu sighed once more, uncovering his face and sitting up. He pinched the bridge of his nose, eyebrows furrowing as he couldn't believe what he was about to say. "Alright alright, fine. But only this once. And if you tell anyone, I swear I will kill you."

Osomatsu smiled and sat up quickly. He placed a hand on his heart, raising the other one. "I swear that I will not tell a single soul."

Rolling his eyes, Choromatsu grabbed his older brother by the collar of his pajama shirt, tugging him close. With slight hesitation, Choromatsu leaned in, closing his eyes as he locked lips with Osomatsu, resulting in a small squeak coming from the older Matsuno. Osomatsu couldn't believe that Choro caved in and kissed him, which made him smile a little. In a short moment, his eyes fluttered shut, snaking his arms around the small figure and pulling Choromatsu close to him, kissing him back with some soft, sweet tenderness that he never imagined he'd ever do. And for some reason, he felt like he was floating. The longer the kiss lasted, the more he melted into Choromatsu's touch. He never wanted it to end.

Unfortunately for me, Choromatsu showed no signs of continuing the kiss, pulling away after 10 seconds. His face, the same shade as a tomato at this point. He looked at Osomatsu with a look of annoyance. "Happy now?" he asked. He wouldn't say it out loud, but inside he actually felt butterflies, wanting to kiss him again.

With a smile and a nod, Osomatsu let his brother go, lying back down on his side. "Very." He closed his eyes, only to open them again when he felt Choromatsu snuggle up against him, making his heart skip a beat. He smiled a little more, wrapping his arms around him once more and closing his eyes.

"If you tell anyone about this too, I will actually kill you," Choromatsu mumbled, dozing off.

Osomatsu chuckled, holding him gently. "I won't tell anyone..."

 _~end of flashback~_


	2. Chapter 2

"Uuuuugh, there's nothing to do in this house!" Osomatsu groaned as he flopped over on his side, rolling around on the floor. "I hate having days off." 20 years had already passed, and Osomatsu was still living at his parents house. After all his brothers had moved, he felt no need to leave as well.

"You could be out looking for an apartment instead of being lazy," Mamamatsu stated, finishing the last of the morning dishes. She grabbed a towel and dried her hands, turning towards her eldest son. "All of your brothers moved out and started their lives finally. You have a job and enough money saved up, Osomatsu, so why haven't you thought about leaving the house?" She put the towel down and walked over to him, kneeling down. "Not that I don't love taking care of you, but there's no point anymore. You're 35 years old and still living at home."

Osomatsu sat up and crossed his legs, smiling over at his mother. "I never plan on leaving, mom. Not because I want you to take care of me for the rest of your life, but because when you and dad do eventually pass on, I plan on keeping the family house." He lied back down, resting his head on his arms. "So I don't see why I should spend the money I saved on an apartment when I'm just going to move back here."

Mamamatsu sighed and shook her head, letting out a little laugh. "Even after all these years, you're still so persistent on staying here. Then what about going out and getting a girlfriend at least? You can't just stay single forever."

Closing his eyes, Osomatsu shook his head, exhaling softly. "I just don't feel like dating right now. It's not like I'll stay single forever." He looked over at his mom, smiling again. "And you already have grandchildren. Karamatsu has a daughter, and Todomatsu's wife is pregnant. Hell, I even think Jyushimatsu has a kid. So there shouldn't be a rush for me to have kids."

"Well don't forget about Choromatsu!" Mamamatsu exclaimed. "He's only got a girlfriend, but from the way he talks about her, I think he's going to ask her to marry him."

Osomatsu froze, his eyes instantly shooting open. For a moment, he found it hard to move, having to force himself up as he looked at his mother, shocked. "Wait...C-choromatsu has a girlfriend?" He felt his chest tighten at her words. Even after 20 years. Even after just that one kiss, no one else was able to make Osomatsu feel the same way that his younger brother did. But he wasn't about to scream to the world that he was in love with his brother. One, because it was his brother. And two, because after what his mom had just told him, he was pretty sure Choromatsu wouldn't feel the same.

"Mhm. He called a couple months ago and told me about her." A small giggle left Mamamatsu's lips. "Ah, he sounded so lovestruck. To think that not even ten years ago, I was calling all of you NEETs." She sighed, "how time goes by so fast. I'm going to go take a nap. There's some food in the fridge if you get hungry." With that, she got up, patting her son on the head.

Osomatsu was still in shock, clutching his hands into fists as he stared at the floor. _Lovestruck?!_ he thought to himself. _He's not supposed to fall for her, he's supposed to fall for me!_ Osomatsu blinked a couple of times, followed by him shaking his head quickly. "Nonononono, you can't think like that!" He sighed and reached into his pocket, pulling out his phone. He stared for a moment before dialing a number and lifting his phone to his ear. After a few rings, there was a reply. "Hey...it's me."


	3. Chapter 3

"Hey...it's me."

"Osomatsu-niisan?" Choromatsu questioned, being the one on the other side of the line. "Wow it's...it's been a while since you've called. Is something wrong? Are mom and dad okay? They aren't sick right?" Classic Choro to be worried about his family because of a sudden call.

Osomatsu chuckled, sounding a little more nervous than he intended to be. "N-no, no, mom and dad are just fine. Everything's okay." God, he could not sound like he was lying anymore even if he tried. "Mom and I were just talking about you and y'know, thought I would give you a call. See how my little brother is doing." His heart started pounding in his chest. Even the sound of Choromatsu's voice brought Osomatsu back to the night they kissed. "A-also...mom mentioned that you have a girlfriend now."

"Yeah, I do!" The way that Choromatsu sounded from those three simple words - the cheery excited tone - made it clear to Osomatsu that his brother was unbelievably happy. "I was actually planning to have a little family get together so you guys can meet her. She's been dying to see how I was able to survive all those years living with you and the others." He laughed at his own comment, sighing. "I was thinking this Saturday if you aren't busy or if you could take a day off from work."

"T-this Saturday?" Osomatsu gulped hard, feeling sweat starting to form on his forehead. If there was anything he didn't want to do, he really didn't want to meet the girl who could potentially take Choromatsu from him. Osomatsu furrowed his brows and shook his head quickly. _You can't think like that!_ he thought to himself. _He is your brother. You can't be in love with your brother. You can't get mad that he has no interest in you! Get over yourself, Oso. It's time to move on!_ But even all the mental lectures he would give himself, Osomatsu knew that it wouldn't be enough to get him to move on. He cleared his throat, speaking up again. "Yeah, I think I can take time off of work to meet this mystery girl of your's." That sounded so half-assed, but it was too late to save himself now.

"Awesome! I'll call the others and see if Saturday works for them too. Talk to you later, Osomatsu-niisan!" There was a small silence, and Osomatsu was close to hanging up before he head his brother's voice again. "Oh wait! Niisan wait!" He blinked a couple times, lifting the phone to his ear again. "Before I go, I should mention that there's some really important news that I want to tell you and the others, so I really hope you can come!" Osomatsu bit his bottom lip, his heart skipping a beat at Choromatsu's excitement. "Goodbye Osomatsu-niisan. Hopefully I'll see you this weekend." And with that, Choromatsu hung up.

Osomatsu closed his phone, clutching it tightly. "How will I be able to face him..." He fell back, staring up at the ceiling. "If I see her, I won't be able to hide it from him. He'll know right away." He side, covering his face. "What do I do?" Slowly, he rolled over to his side, opening his phone and scrolling through all of his pictures. A small smile crept on his lips as he stopped on the selfie he took with Choromatsu the last time the were together. Choromatsu was unaware that Osomatsu had his phone out, so when the picture was taken he wasn't smiling. He was looking at the camera with an expression of shock and horror. The look that made Osomatsu's heart do flips and his stomach fill with butterflies.

He would never admit to anyone that he ever had that feeling. Even if it wasn't for his younger brother, Osomatsu knew that if his family found out that anyone was able to give him butterflies, they would never let him live it down. He smiled more as he stared at the picture, memories flooding his mind. He started thinking about everything he and Choromatsu did together. From the kiss to embarrassing his younger brother in front of his idol to even walking in on him that one time, ultimately giving him the nickname Fappymatsu. Osomatsu remembered all the nights that he woke up to Choromatsu crying about something, whether it was a dream or his insecurities. How he would let Choro know that he was awake with him. How he would hold him until he calmed down and would go back to sleep until he knew that Choromatsu was okay.

With every memory that he had of them, Osomatsu's smile faded, groaning and whining as he closed his phone and curled up. "It's impossible. There's no way," he softly said to himself. "There's no way I'll be able to move on..."


	4. Chapter 4

Minutes turned into hours. And those hours turned into days. And soon enough, it was Saturday. Osomatsu had been dreading weekend's arrival ever since Choromatsu had decided to have a little family party. He wanted any possible excuse not to go, no matter how badly he wanted to see his brother. Just not with his girlfriend. If it were just the two of them, Osomatsu wouldn't be so reluctant to call out of work and head over to Choromatsu's house. But after telling the parents, there was no way of getting out of it. He just hoped that he would be able to keep his cool the entire time.

Osomatsu bit his bottom lip as he walked up the driveway of his younger brother's house, taking in all the scenery. Out of all the Matsuno brothers, Choromatsu was definitely the most successful. He was the first to get a house instead of an apartment. Not only that, but his house had the most fantastic view of the sea. Osomatsu smiled a bit before his nerves started taking over, making him hesitate before knocking on the door. He gulped hard, hearing footsteps from inside. He smiled when the door opened, seeing Choromatsu's face for the first time in months.

"Osomatsu-niisan, you made it!" Osomatsu's heart started to flutter as the blood instantly rushed to his cheeks, turning them a bright red. _God, he's still so cute. How can someone be so cute!?_ He cleared his throat, trying to say something, but unable to find the right words. Choromatsu gave him a slightly worried look, stepping forward a bit. "Niisan, are you alright? You're turning red, are you sick?" He lifted his hand, pressing it to Osomatsu's forehead. Which only made him blush even more.

"I-I, u-uh..." Osomatsu stuttered out, taking a deep breath to gain at least a little confidence to speak. "Y-yeah, I'm fine. It's just really warm out here." He knew this would happen the moment he saw Choromatsu, and hopefully he would be able to lie his way through the day to keep from anyone getting suspicious.

Choromatsu grabbed his hand, pulling him inside quickly. "Everyone else is already here. I just wanted to wait for you to get here so I can give everyone the big news!" He lead his older brother through the house, sliding open the door to the living room. Everyone turned their heads and shouted Osomatsu's name, which made him smile. He walked over and sat with the rest of his family, Karamatsu wrapping an arm around his neck and pulling him close.

Everyone turned their heads towards Choromatsu when he cleared his throat. "Osomatsu-niisan, since you were the last one year, you haven't gotten the chance to meet my girlfriend yet." A young-looking lady stood up from the table. Her brunette hair was long and up in a ponytail. She had beautiful sparkling eyes and pretty much flawless skin. In anyone's eyes, she was perfect. Choromatsu slid his arms around the girl's waist, pulling her close. "Niisan, this is Emi." He looked around at his family, smiling brightly. "And...Emi and I have decided to get married. We know it's sudden, but..." he looked over at his girlfriend, smiling happily, "I already know that she's the one I want to spend my life with."

There were a few shared gasps between some of the brothers. But most of them started cheering and congratulating Choromatsu on his engagement. Everyone...except for Osomatsu. His eyes had widened, suddenly feeling like he was the only one on the room. Not even Choromatsu was there with him. He could feel his heart shattering. Any hope that Osomatsu had that his younger brother would one day return his feelings had vanished with those few simple words. He wanted to cry. He wanted to scream at Choromatsu that he couldn't get married. That he couldn't fall in love with Emi, that he was supposed to fall in love with him. But he couldn't. He hung his head, feeling the tears stinging his eyes.

"Osomatsu-niisan?" Todomatsu said, placing a hand on his eldest brother's shoulder. "Are you crying?"

Hesitating, Osomatsu looked up as the tears rolled down his cheeks. He smiled through the pain in his chest, rubbing the back of his neck, letting out a soft laughed. "Y-yeah, sorta. I-I'm just proud of my baby brother." He opened his eyes and looked at him, giving him a thumbs up before shakily getting to his feet. "Good job, Choromatsu. E-excuse me, but...I-I realized I have something important I have to do." He quickly turned around and started running towards the front door, covering his mouth to muffle any sobs that tried to escape. He ran outside and around the house to an area he knew he could hide and cry in peace.

"O-Osomatsu-niisan, wait!" Choromatsu shouted, excusing himself after Osomatsu had already made it outside. He chased after him, looking in every corner he could to find his older brother. He bit his bottom lip, worrying more and more the longer it took to find him. Then he heard it. The faint sound of sobs come from underneath the deck. Choromatsu quickly followed the sound, finding his brother hugging his knees tight, his body trembling as he cried. "Osomatsu-niisan?" He said softly, walking over to him and kneeling down. "What's wrong? Why are you crying?"

"How..." Osomatsu managed to say, the word muffled by arms covering his face.

Choromatsu raised a brow, looking at him confused. "How what?"

"How can you be getting married..?" The eldest Matsuno looked up, tears streaming down his cheeks like two little waterfalls. "H-how can you just say you're in love a-after only a few months."

"I..." Choromatsu gulped, not knowing what to say. "I-I don't know what you mean, niisan. A-aren't you happy that I found someone?"

Osomatsu stared at his brother for a moment before looking away, mumbling. "It should've been me..." It was silent before he covered his eyes, his entire body trembling as the tears kept coming. "It should've been me that you fell for! I should've been the one you fell in love with!" He couldn't calm down, all his feelings coming out at once. "You have no idea how hard it is to be in love with your brother knowing it's never going to fucking happen. You have no idea...h-how hard it is knowing I've lost completely." Osomatsu couldn't look at Choromatsu. He didn't want to see the look on his face. "I-it should've been me..." he sobbed out.

Choromatsu's eyes widened as he listened to his brother's words. For moments that felt like forever, he didn't know how to respond. He felt like anything he would say or do would only make the situation worse. Slowly, his head hung, speaking up. "I-it's been twenty years, Osomatsu-niisan..." It was silent for a while, Osomatsu looking up. "It's been twenty years, and all this time I thought you forgot." Tears slowly started making their way down Choromatsu's cheeks. "A-after that night, I thought I was insane. I thought I had gone crazy because the only thing I wanted to do was kiss you again. B-but I knew it would be wrong, a-and I assumed that you only wanted to try it once. That it was nothing." He looked up, locking eyes with Osomatsu. "I never thought that I would fall in love with a guy, let alone my own brother."

Osomatsu blinked a few times, shocked. "You...you were in love with me?"

Choromatsu nodded. "For so long. I wanted to tell you, but I didn't want to risk losing you." He shook his head, looking away. "All that's in the past now. I'm engaged...with a beautiful girl. It's for the best, niisan. So...you should move on now."

Osomatsu furrowed his eye brows, grabbing Choromatsu by the collar of his shirt. "No...there's no way...not yet." He looked him dead in the eye. "There's no way you could've given up so easily!"

Choromatsu gulped, hands trembling. "W-we're brothers...i-it wouldn't be right. N-no one would've understood!"

"Maybe not...but tell me you're over me after this." Without hesitation, he pulled Choromatsu close, pressing their lips together. Choromatsu's eyes widened, and he ready to push his brother away. But instead, he found himself melting into the kiss. His eyes fluttered shut, shakily wrapping his arms around Osomatsu's neck, not fighting back anymore, kissing him sweetly.

Choromatsu pulled away after a few moments, looking at Osomatsu. He bit his bottom lip, his cheeks turning pink as he said, "I...I-I'm still in love with you...Osomatsu-niisan..."


End file.
